Probing the Solution-Phase Dynamics of l3-Iodanes and Relation to Reactivity

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In this project, funded by the Chemical Structure, Dynamic & Mechanism B Program of the Chemistry Division, Professor David Stuart of the Department of Chemistry at Portland State University is studying organoiodine chemical reagents. The goal of this research is to understand how the molecular structure and the reaction medium interact to influence overall behavior of these compounds in chemical reactions. The project lies at the interface of physical and synthetic organic chemistry with eventual applications in health, agriculture, and technology; it is well-suited to the training of scientists in a higher-education setting. Portland State University is a diverse institution and is well-positioned for training underrepresented students in sciences. Collaboration between the Professor Stuart's group and the fine-chemical industry will facilitate a more rapid translation of fundamental discoveries into applications by the broader scientific community.Hypervalent iodine reagents are routinely used as catalysts, initiators, reagents, and oxidants in chemical synthesis because they integrate well with established and emerging reactivity paradigms such as ionic, metal-mediated/catalyzed, and radical reactions. Electrostatic interactions are an integral component of bonding in the expanded coordination of hypervalent iodine compounds and the hypothesis is that they occur during aggregation and Lewis acid-base chemistry with a direct impact on reactivity and applications. The goal of this project is to unravel the structure and solvent effects that influence solution-phase interactions of hypervalent iodine compounds with a clear link to reaction chemistry. This is to be achieved by synthesizing designed libraries of monoaryl and diaryliodonium compounds, conducting nuclear magnetic resonance and mass spectrometry titration experiments, fitting titration data to binding models by non-linear regression, and analyzing linear Free-energy relationships and reaction kinetics. A deeper understanding of the behavior of hypervalent iodine in the solution phase will be obtained by 1) quantifying and exploiting the Lewis acidity of aryl(2,4,6-trimethoxyphenyl)iodonium salts and related derivatives, 2) assessing the influence of solution-phase aggregation of these salts on reactivity and selectivity, and 3) activation of aryl iodanes with Bronsted-Lowry acids.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.